Get over yourselves: Life in the multiverse could be commonplace

Dark energy clue comes to light

A universe containing life like ours is probably more common in the multiverse than previously thought, according to new theoretical studies.

The idea of multiple universes existing in parallel has gained traction in the last few decades and boffins are throwing large chunks of computing power at the problem, testing out theoretical models. Now a simulation team think the mulitverse theory could help explain the amount of dark energy in our neighborhood, and why life might be more common than we thought.

Researchers from the Durham University, the University of Sydney, Western Sydney University, and the University of Western Australia, created different simulated models of the universe from the British-based EAGLE (Evolution and Assembly of GaLaxies and their Environments) project.

No, Stephen Hawking's last paper didn't prove the existence of a multiverse

EAGLE allows users to grow universes under different starting conditions such as its star formation rate and the number of active black holes using computer simulation. The models show how these properties affect how a universe evolves over time.

A key ingredient to the simulation is dark energy. Cosmologists don’t quite understand the nature of this mysterious force, but believe it is driving the expansion of our universe. Current models predict much more dark energy than what has been observed.

If there is too much of it, however, it means that matter will be too diluted to come together to create stars, galaxies, planets and ultimately, life.

"We asked ourselves how much dark energy can there be before life is impossible?,” said Pascal Elahi, co-author of the paper and a research fellow at the University of Western Australia.

The results published in the Monthly Notices of the Royal Astronomical Society show that even if the amount of dark energy in the universe was cranked up to a few hundred times the amount actually observed, it would only have a limited amount of impact.

"For many physicists, the unexplained but seemingly special amount of dark energy in our Universe is a frustrating puzzle.

"Our simulations show that even if there was much more dark energy or even very little in the Universe then it would only have a minimal effect on star and planet formation, raising the prospect that life could exist throughout the Multiverse," Jaime Salcido, first author of the paper and a postgraduate student in Durham University, said.

Our universe could be one of many

Scientists have struggled to explain why the universe has the properties we observe today. Some theories call upon the weak anthropic principle, the idea that the universe is the way it is today and can obviously support life because we exist. But it is not special in any way. It just so happens to be compatible with life because we observe it to be.

The properties of our universe are, in fact, down to the multiverse. “Many models of inflation, such as eternal inflation, imply that the Universe as a whole is composed of a vast number of inflationary patches or sub-universes. Each sub-universe inherits a somewhat random set of physical constants and cosmic parameters from a wide range of possible values,” the paper said.

Our universe is just a sub-universe - a small part of the multiverse. The researchers said their results disagree with the idea of a multiverse to explain the amount of dark energy we have in our universe.

If we do live in a multiverse, then we should see up to 50 times more dark energy than what has actually been observed.

"The formation of stars in a universe is a battle between the attraction of gravity, and the repulsion of dark energy”, Richard Bower, co-author of the paper and a physics professor at Durham University, asked.

"We have found in our simulations that universes with much more dark energy than ours can happily form stars. So why such a paltry amount of dark energy in our Universe?"

The results don’t rule out the idea of the multiverse completely, however. They believe that the tiny amount of dark energy could be explained by a new law of nature that has not been discovered yet.

"I think we should be looking for a new law of physics to explain this strange property of our Universe, and the Multiverse theory does little to rescue physicists' discomfort," Bower said. ®